It has long been recognized that venous-arterial bypass with a membrane lung, also called ECMO (extracorporeal membrane oxygenation), is a reasonable option to assist a failing heart, except that there continues to be no really satisfactory way to decompress the left heart. To overcome this handicap, it has been proposed to decompress the left atrium by a large catheter passed into the vena cava, and puncturing the interatrial septum. An alternative suggested was to pass a large bore catheter through the aorta across the aortic valve into the left ventricle. Both such proposals carry substantial morbidity.
As a possible alternative, mechanical means can be used to assist the failing circulation; however, this require implantation, e.g. one or two blood pumps which in turn requires the opening of the chest. Upon recovery, the chest must be again opened to remove the blood pumps. In addition, such implantation is time consuming, it entails a major commitment, and is very high in cost. A major complication related to this practice is bleeding, and infection occurs in over one-half of the patients so treated.
In another context, coil spring devices are known for use in supporting damaged blood vessels to prevent them from collapsing. It has been proposed to make these coils from so-called memory metal (Nitinol) noting the Dotter U.S. Pat. No. 4,503,569; also see U.S. Pat. No. 3,868,956. In Maass et al U.S. Pat. No. 4,553,545, various shapes and configurations are suggested whereby the coil can be expanded from a smaller diameter state to a larger diameter state, again for the purpose of preventing damaged blood vessels and the like from collapsing.